Ventilating water closets by driving air from the bowl through the flush rim has long been recognized as a very efficient method for odor removal but are still not coming to a wide spread use. Some systems which withdrawal this air from the standpipe in a toilet tank and above the level of water in the water tank and are adapted for installation on existing toilets are disclosed in U.S. Pat. Nos. 3,703,010, 3,763,505, 4,165,544, 4,232,406, 4,582,250, 5,029,346, and 5,321,856. The systems disclosed in U.S. Pat. Nos. 4,044,408, and 5,029,346 resolve the problems of water vapor intrusion. Some systems which resolve the problem of undesirable suction when the toilet is flushed are disclosed in U.S. Pat. Nos. 3703010, 4165544, 4582250, and 5029346.
The methods disclosed in the patents have the major disadvantage of not being adapted for easy mounting and that a particular element is only adapted to a particular water tank design.
The method disclosed in the U.S. Pat. No. 5,321,856 has the disadvantage of poor sealing when the water tank upper edge presents irregularities.